1. Field of the Invention
The present invention relates to a wear-resistant structure in which a surface of a base body is coated with a film constituted of at least one or more of nitride, nitrooxide, carbonitride, and carbonitrooxide that contain titanium.
2. Description of the Related Art
Conventionally, in order to improve wear resistance and fracture resistance of metal cutting tools, a technique of coating a surface of a base body with a hard film of TiC, TiN, TiCN or the like that is harder than the base body by physical vapor deposition (PVD) or chemical vapor deposition (CVD) has been generally used widely.
In addition, recently, as well as the increase of request for high speed machining or high feed machining in order to reduce machining cost, for hard-to-cut materials such as stainless steel and nickel-based alloy has been required. In particular, as a hard film for PVD coated tools, which is excellent in the balance of fracture resistance and wear resistance and the use amount of which is increasing year by year, the most prevailing TiN or TiC films, and further a Ti(C,N) film, a (Ti, Al)N film, and the like film are commercialized.
With respect to such a hard film for use in cutting tools, the present applicant proposed in Japanese Unexamined Patent Publication JP-A 6-248420 (1994) that, in a surface-coated body constituted by coating the surface of a base body with a hard film formed of at least one or more selected from metal carbide, nitride and oxide, a hard film having high hardness and excellent adhesiveness with a base body can be manufactured by containing 0.01-25% by atom of at least one or more inert gas elements selected from He, Ne, Ar, Kr and Xe in the hard film to create a high residual compression stress to the surface of the film.
Although the method in which a predetermined volume of inert gas component is added in film forming can enhance the hardness of the hard film to improve the wear resistance of the film, the fracture resistance of the film was insufficient. For example, in a case of using the film for a cutting tool, the cutting edge part of the hard film suffers from chipping or fractures caused therein from the early period of cutting, resulting in deterioration in accuracy of a machined surface, or poor sliding properties cause troubles in the cutting.